Giant island mice exhibit widespread gene expression changes in key metabolic organs

Abstract
Island populations repeatedly evolve extreme body sizes, but the genomic basis of this pattern remains largely unknown. To understand how organisms on islands evolve gigantism, we compared genome-wide patterns of gene expression in Gough Island mice, the largest wild house mice in the world, and mainland mice from the WSB/EiJ wild-derived inbred strain. We used RNASeq to quantify differential gene expression in three key metabolic organs: gonadal adipose depot, hypothalamus and liver. Between 4,000 and 8,800 genes were significantly differentially expressed across the evaluated organs, representing between 20 and 50% of detected transcripts, with 20% or more of differentially expressed transcripts in each organ exhibiting expression fold changes of at least 2X. A minimum of 73 candidate genes for extreme size evolution, including Irs1 and Lrp1, were identified by considering differential expression jointly with other data sets: (i) genomic positions of published ...